Ellipse Using Mid Point Algorithm C++ Program

#include<conio.h>

#include<stdio.h>

#include<Graphics.h>

void main() {

int gd = DETECT,gm;

initgraph(&gd,&gm,"C:\\TC\\BGI");

int xc,yc,x,y;

long rx,ry;

float d;

printf("Enter Coordinates of Centre of Ellipse: ");

scanf("%d%d",&xc,&yc);

printf("Enter Radius along X-AXIS: ");

scanf("%ld",&rx);

printf("Enter Radius along Y-AXIS: ");

scanf("%ld",&ry);

//Region 1

d=((ry*ry)-(rx*rx*ry)+(rx*rx))/4;

x=0;       y=ry;

while(2.0*ry*ry*x < = 2.0*rx*rx*y)

{

       if(d < 0)

       {

             x++;

             d = d+(2*ry*ry*x)+(ry*ry);

       }

       else

       {

             x++;y--;

             d = d+(2*ry*ry*x)-(2*rx*rx*y)-(ry*ry);

       }

       putpixel(xc+x,yc+y,15);

       putpixel(xc+x,yc-y,15);

       putpixel(xc-x,yc+y,15);

       putpixel(xc-x,yc-y,15);

}

//Region 2

d =ry*ry*(x+0.5)*(x+0.5) + (rx*rx*(y-1)*(y-1)) - (rx*rx*ry*ry);

   while(y > 0)

   {

       if(d<= 0)

       {

             x++;    y--;

             d = d + (2*ry*ry*x) - (2*rx*rx*y) + (rx*rx);

       }

       else

       {

             y--;

             d = d - (2*rx*rx*y) + (rx*rx);

       }

       putpixel (xc+x,yc+y, 15 );

       putpixel (xc+x,yc-y, 15 );

       putpixel (xc-x,yc+y, 15 );

       putpixel (xc-x,yc-y, 15 );

   }

getch();

closegraph();

}

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